Interposer configured to reduce the profiles of semiconductor device assemblies, packages including the same, and methods

ABSTRACT

An interposer includes a substrate, a conductive structure configured to contact the back side of a semiconductor device and contact pads. The interposer may include first and second sets of contact pads carried by the substrate. The interposer may also include conductive traces carried by the substrate to electrically connect corresponding contact pads of the first and second sets. The receptacles, which may be formed in a surface of the substrate and expose contacts of the second set, may be configured to at least partially receive conductive structures that are secured to the contact pads of the second set. Thus, the interposer may be useful in providing semiconductor device assemblies and packages of reduced height or profile. Such assemblies and packages are also described, as are multi-chip modules including such assemblies or packages. In addition, methods for designing and fabricating the interposer are disclosed, as are methods for forming assemblies, packages, and multi-chip modules that include the interposer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 10/150,893,filed May 17, 2002, now U.S. Pat. No. 7,145,225 B2, issued Dec. 5, 2006,which is related to U.S. patent application Ser. No. 09/944,465, filedAug. 30, 2001, and titled MICROELECTRONIC DEVICES AND METHODS OFMANUFACTURE; now U.S. Pat. No. 6,756,251, issued Jun. 29, 2004, and tothe following U.S. Patent Applications filed on even date herewith: Ser.No. 10/150,892, filed May 17, 2002, and titled METHOD AND APPARATUS FORFLIP-CHIP PACKAGING PROVIDING TESTING CAPABILITY, pending; Ser. No.10/150,516, filed May 17, 2002, and titled SEMICONDUCTOR DIE PACKAGESWITH RECESSED INTERCONNECTING STRUCTURES AND METHODS FOR ASSEMBLING THESAME, now U.S. Pat. No. 7,112,520, issued Sep. 26, 2006; Ser. No.10/150,653, filed May 17, 2002, and entitled FLIP CHIP PACKAGING USINGRECESSED INTERPOSER TERMINALS, now U.S. Pat. No. 7,161,237, issued Jan.9, 2007; Ser. No. 10/150,902, filed May 17, 2002, and entitled METHODAND APPARATUS FOR DIELECTRIC FILLING OF FLIP CHIP ON INTERPOSERASSEMBLY, now U.S. Pat. No 6,975,035, issued Dec. 13, 2005; and Ser. No.10/150,901, filed May 17, 2002, and entitled METHODS FOR ASSEMBLY ANDPACKAGING OF FLIP CHIP CONFIGURED DICE WITH INTERPOSER, now U.S. Pat.No. 7,348,215, issued Mar. 25, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to interposers for packaging semiconductordevices with array-type connection patterns. In particular, the presentinvention relates to tape-type interposers that are useful insemiconductor device assemblies and packages of reduced package height,or profile, and to semiconductor device assemblies and packages ofreduced profile. The present invention also relates to methods forfabricating the tape-type interposers and to methods for formingsemiconductor device assemblies and packages that include the tape-typeinterposers.

2. State of the Art

Conventionally, semiconductor dice have been packaged in plastic or,less commonly, in ceramic packages. Packages may support, protect, anddissipate heat from semiconductor dice. Packages may also provideexternal connective elements for providing power and signal distributionto and from semiconductor dice, as well as for facilitating electricaltesting, such as burn-in testing and circuit evaluation, ofsemiconductor dice prior to or after assembly thereof with higher-levelcomponents, such as carrier substrates or circuit boards.

The ever-decreasing sizes of electronic devices, such as cellulartelephones, handheld computers, and portable computers, have driven theneed for semiconductor device assemblies and packages withever-decreasing profiles, as well as the need for semiconductor deviceassemblies and packages that consume ever-decreasing amounts of thesurface areas, or “real estate”, of carrier substrates, such as circuitboards.

The need for semiconductor device assemblies and packages that consumeever-decreasing amounts of real estate has been met by use of externalconnection technologies, such as so-called “flip-chip” connections, inwhich a semiconductor device is positioned over a carrier therefore inan inverted orientation with contact pads (e.g., bond pads of a baresemiconductor die or contacts of a semiconductor device assembly orpackage) of the semiconductor device and corresponding terminal pads ofthe carrier in alignment with one another. Flip-chip type connectionsprovide the desired number of connections to a semiconductor devicewithout requiring that an assembly or package that includes thesemiconductor device have peripheral edges that extend a substantialdistance beyond the peripheral edges of the semiconductor device. Thistype of semiconductor device assembly or package is typically referredto as a “grid array” package (e.g., a ball grid array (BGA) package orpin grid array (PGA) package) due to the arrangement of input and outputcontacts thereof in a grid array connection pattern. Such contact padarrangements facilitate the use of a greater number of connections thanwould otherwise be possible when contact pads are arranged only alongthe periphery of an interposer.

Grid array semiconductor device assemblies and packages typicallyinclude an interposer to which one or more semiconductor dice may besecured and electrically connected. A substrate of the interposer may beformed from a variety of different, typically electrically insulative orinsulator-coated materials, including flexible materials, such aspolymer (e.g., polyimide) films or tapes, and rigid materials, such assilicon, glass, ceramic, or organic materials (e.g., FR-4 resin).

Interposers for use in grid array assemblies and packages also typicallyinclude conductive traces that extend between first and second sets ofcontacts, with each of the foregoing being carried by the interposersubstrate. Contacts of a first set are electrically connectable tocorresponding bond pads of a semiconductor die. Contacts of a second setare configured for making external electrical connections to otherelectronic components, such as circuit boards or other semiconductordevices. When the first and second sets of contacts are on oppositesides of the interposer, conductive vias may be positioned along one ormore conductive traces to facilitate communication between contact padsof the first set and their corresponding contact pads of the second set.The first and second sets of contact pads are arranged in such a way asto redistribute the locations of the bond pads of a semiconductor devicesecured to the interposer. Such redistribution may provide for a contactpad arrangement that is more desirable than the arrangement of bond padson the semiconductor device, for a contact pad that is more useful thanthe bond pad arrangement in flip-chip applications, for increasedspacing or pitch between adjacent contact pads relative to that betweencorresponding, adjacent bond pads of the semiconductor device, or somecombination of these features.

When such an interposer is assembled with a semiconductor device, thecontact pads of the first group are typically connected to correspondingbond pads of the semiconductor device by way of discrete conductiveelements, such as bond wires, conductive tape-automated bond (TAB)elements carried upon a flexible, dielectric substrate, or by so-called“flip-chip” bonding techniques, which employ conductive structures suchas balls, bumps, columns, or other structures formed from conductivematerial, such as metal, metal alloy (e.g., solder), conductive orconductor-filled polymer, anisotropically (i.e., z-axis) conductiveelastomer, or the like.

An interposer-semiconductor device assembly may communicate withelectronic components external thereto by way of external conductiveelements, such as conductive balls, bumps, columns, pins, or otherstructures, that extend from contact pads of the second set. When solderballs are employed, the connection pattern of such a semiconductordevice assembly is termed a “ball grid array” (BGA) connection patternor a “fine ball grid array” (FBGA) connection pattern, depending uponthe spacing or pitch between adjacent solder balls. Similarly, when pinsare used as the external conductive elements of such an assembly, theconnection pattern of the assembly may be referred to as a “pin gridarray” (PGA) connection pattern.

Conventionally, the thicknesses of such assemblies are defined by thecumulative thicknesses of the interposer, the adhesive material securinga semiconductor device thereto, the semiconductor device, the distancebond wires protrude above an active surface of the semiconductor device,and the distance external conductive elements extend from theinterposer.

Several interposer designs have been developed to address the need forsemiconductor device assemblies and packages of ever-decreasingprofiles. For example, some rigid interposers include recesses forreceiving all or part of a semiconductor device. The recesses of suchinterposers may also be configured to receive all or part of thediscrete conductive elements (e.g., bond wires) that electricallyconnect bond pads of a semiconductor device to corresponding contactpads of the interposer. The profiles of grid array-type assemblies orpackages including such interposers are typically defined by acombination of the thickness of the interposer, the distance thatdiscrete conductive elements protrude above a surface of the interposer,and the height of conductive structures protruding from an oppositesurface of the interposer. While these grid array packages are thinnerthan their predecessors by an amount equal to the full or partialthicknesses of the semiconductor devices and adhesive layers thereof, itis difficult, if not impossible, to further decrease their profiles.

Accordingly, there are needs for semiconductor device assemblies andpackages having reduced profiles, as well as for an interposerconfigured to impart an assembly or package including the same with athinner profile.

BRIEF SUMMARY OF THE INVENTION

The present invention includes an interposer that may be used insemiconductor device assemblies and packages to impart such assembliesor packages with relatively thin profiles. In addition, the presentinvention includes flip-chip type semiconductor device assemblies andpackages that include such interposers. The present invention alsoincludes methods for fabricating the inventive interposers.

An interposer incorporating teachings of the present invention includesa thin substrate with at least one attach region. Each attach region ofthe interposer is configured to receive one or more semiconductordevices (e.g., one or more semiconductor dice). A first set of contactpads is positioned at or proximate to the attach region so that discreteconductive elements (e.g., bond wires, conductive tape-automated bonding(TAB) elements carried upon a dielectric film, leads, or conductivestructures such as balls, bumps, columns, pins, etc., formed fromconductive material) may appropriately connect bond pads of the one ormore semiconductor devices to corresponding contact pads of the firstset. Each contact pad of the first set, or first contact pad, may beelectrically connected to a corresponding contact pad of a second set,or second contact pad, by way of a conductive trace that extendstherebetween.

In addition, an interposer according to the present invention mayinclude a ground plane, a thermally conductive structure, which may formall or part of a thermal transfer element, or a combination thereof. Ifany of these structures are present, they may be formed on the samesurface of the interposer as that on which a die attach region islocated and extend proximate to or at least partially into the dieattach region. If these structures extend into the die attach region,they may comprise a part of the die attach region so as to be in contactwith a semiconductor device upon placement thereof in that die attachregion.

The interposer may also include “dummy” contact pads that do notcommunicate with a bond pad of the semiconductor device. Instead, thedummy contact pads may communicate with or comprise a part of a groundplane and/or a thermally conductive structure of the interposer. Dummycontact pads that communicate with or that are part of a thermallyconductive structure of the interposer may be positioned so as tofacilitate the transfer of heat away (i.e., the dissipation of heat)from a semiconductor device secured to the interposer or from anassembly or package that includes the interposer.

Each of the contact pads and conductive traces of the interposer may becarried upon the same, first surface thereof and in a single layer.Alternatively, the first and second sets of contact pads may be carriedon opposite surfaces of the interposer substrate, with at least portionsof the conductive traces, or electrically conductive vias positionedalong the lengths thereof, being carried internally within theinterposer substrate.

An interposer that incorporates teachings of the present invention alsoincludes recesses that are configured to partially receive conductivestructures, such as balls, bumps, columns, or pins. The recesses may beformed in a second surface of the interposer substrate, which isopposite from the first surface thereof or, if a semiconductor device isto be secured to the interposer in a flip-chip orientation, in the firstsurface of the interposer substrate. Each recess exposes and, thus,communicates with at least a portion of a surface of a correspondingsecond contact pad, dummy contact pad, or a portion of a ground planeand/or thermally conductive structure. The recesses may be arranged in agrid array or otherwise, as desired or required, to effect electricalconnection to higher-level packaging.

A method for forming the interposer includes forming the first, second,and dummy contact pads, as well as the conductive traces, from one ormore layers of conductive material on the interposer substrate. If oneor both of a ground plane and a thermally conductive structure aredesired, these structures may also be formed from the layer or layers ofconductive material. By way of example only, each layer of conductivematerial may be laminated onto at least a portion of a surface of theinterposer substrate or deposited thereon (e.g., by physical vapordeposition (PVD), such as sputtering, or by chemical vapor deposition(CVD)). Also by way of example and not to limit the scope of the presentinvention, the conductive features may be formed by known patterningprocesses. The recesses may be formed in the second surface of theinterposer substrate at locations that correspond to the positions ofeach of the second contact pads and the dummy contact pads to whichelectrical connection is desired. Any suitable process may be used toform the recesses, including, without limitation, mask and etchprocesses that are appropriate for the material of the interposersubstrate, laser ablation, die cutting or punching, drilling, milling,or other means known in the art. Formation of the recesses may beeffected either before or after formation of the conductive features.

An assembly according to the present invention includes the interposerwith at least one semiconductor device secured to a corresponding dieattach region thereof. Each semiconductor device of such an assembly orpackage may be attached to a corresponding die attach region of theinterposer as known in the art, such as by use of an adhesive material,an adhesive-coated element (e.g., adhesive-coated tape), or otherwise.If the die attach region of the interposer includes a thermallyconductive structure, a thermally conductive adhesive material may beused to secure the semiconductor device to the interposer and in thermalcommunication with the thermally conductive structure thereof. Bond padsof each semiconductor device may be electrically connected tocorresponding first contact pads. Second contact pads that correspond toeach first contact pad in communication with a bond pad of asemiconductor device have conductive structures, such as balls, bumps,columns, or pins formed from conductive material, secured thereto. Eachof the conductive structures is partially contained within the recessthat corresponds to the second contact pad to which that conductivestructure is secured. In addition, if dummy contact pads are present onthe interposer, one or more of the dummy contact pads may haveconductive structures secured thereto. Conductive structures thatcorrespond to dummy contact pads of the interposer may also be partiallycontained within corresponding recesses.

The use of a relatively thin interposer substrate that at leastpartially encompasses the conductive structures may reduce the overallheight, or profile, of a semiconductor device assembly or packagerelative to an equivalent assembly or package with conductive structuresthat are not recessed relative to the interposer thereof.

Further, if the interposer of such a semiconductor device assembly orpackage includes a thermal transfer element or other thermallyconductive structure in contact with the semiconductor device of theassembly or package, conductive structures that communicate with dummycontact pads or with the thermally conductive structure itself mayprovide enhanced thermal dissipation from the semiconductor deviceduring operation thereof. In such an embodiment, the semiconductordevice is oriented on the interposer in such a way that the thermaltransfer element or other thermally conductive structure of theinterposer and the semiconductor device are in contact with one another.

Assemblies according to the present invention that include more than onesemiconductor device are referred to as multi-chip modules (MCMs). AnMCM may be formed by stacking multiple assemblies of the presentinvention with adjacent assemblies electrically connected to one anotherby way of electrical connections between conductive structuresprotruding from an upper semiconductor device assembly and correspondingcontact pads of a third set, or third contact pads, on an interposer ofan underlying semiconductor device assembly. Each of the contact pads ofthe underlying assembly may communicate with either a first contact padand, thus, a corresponding bond pad of a semiconductor device of thatassembly or a second contact pad of the underlying assembly which, inturn, communicates with a conductive structure secured thereto.

Alternatively, the semiconductor devices of an MCM that incorporatesteachings of the present invention may be stacked relative to oneanother or positioned at different locations on a single interposer andelectrically connected to that interposer by discrete conductiveelements positioned between bond pads of the semiconductor devices andcorresponding first contact pads of the interposer.

A semiconductor device package according to the present inventionincludes an assembly with a suitable encapsulant or packaging materialat least partially protecting one or both of a semiconductor device ofthe assembly and discrete conductive elements that electrically connectbond pads of the semiconductor device assembly and corresponding firstcontact pads of the interposer.

Other features and advantages of the present invention will becomeapparent to those of ordinary skill in the art through consideration ofthe ensuing description, the accompanying drawings, and the appendedclaims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, which illustrate exemplary embodiments for carrying outthe invention:

FIG. 1A is top view of an interposer incorporating teachings of thepresent invention;

FIG. 1B is a top view of an interposer area depicted in FIG. 1A;

FIG. 1C is a cross-sectional representation of the interposer areadepicted in FIG. 1B;

FIG. 2A is a cross-sectional representation of a semiconductor devicepackage incorporating the teachings of the present invention;

FIG. 2B is a cross-sectional representation of a variation of thesemiconductor device package illustrated in FIG. 2A;

FIG. 2C is a cross-sectional representation of the semiconductor devicepackage illustrated in FIG. 2A with an increased thermal element areafor heat dissipation;

FIG. 2D is a cross section of the semiconductor package illustrated inFIG. 2A with both an increased thermal element area and thermallyconductive structures attached thereto;

FIG. 2E is a cross-sectional representation of the semiconductor devicepackage illustrated in FIG. 2A with an increased area for thermallyconductive structures and at least one heat transfer element attachedthereto;

FIG. 3 is a cross-sectional representation of an exemplary embodiment ofa multi-chip module incorporating teachings of the present invention, inwhich a series of separately packaged semiconductor devices arepositioned in a stacked arrangement;

FIG. 4A is a cross-sectional representation of another exemplaryembodiment of a multi-chip module incorporating teachings of the presentinvention, wherein semiconductor devices are stacked over andelectrically connected to a single interposer;

FIGS. 4B, 4C, and 4D are cross-sectional representations of variationsof the multi-chip module in FIG. 4A;

FIG. 5 is a cross-sectional representation of another exemplaryembodiment of an interposer of the present invention, which includes arecess for at least partially receiving a semiconductor device, as wellas a semiconductor device assembly including the interposer;

FIG. 6 is a cross-sectional representation of yet another exemplaryembodiment of an interposer according to the present invention, which isconfigured to have at least one semiconductor device flip-chip bondedthereto, as well as an assembly including the interposer and asemiconductor device;

FIG. 7 is a cross-sectional representation of an interposer thatincorporates teachings of the present invention and includes asemiconductor device flip-chip bonded to the same side thereof as thatfrom which conductive structures protrude, as well as a semiconductordevice assembly including the interposer; and

FIG. 8 is a side view of a multi-chip module including a plurality ofsemiconductor devices positioned at different lateral locations on thesame interposer.

DETAILED DESCRIPTION OF THE INVENTION

The present invention includes an interposer for use in semiconductordevice assemblies and packages, assemblies and packages including theinterposer, and multi-chip modules. The present invention also includesmethods for designing and forming the interposer, as well as for formingsemiconductor device assemblies and packages that include theinterposer.

Referring to FIGS. 1A-1C, an interposer 20 of the present invention isillustrated. The interposer 20 includes a substrate 12, which is alsoreferred to herein as an “interposer substrate,” and at least one layer52 of conductive structures. As depicted, the at least one layer 52 ofconductive structures includes first contact pads 4 located proximate anattach location or region 7 on the substrate 12 and conductive traces 8extending somewhat laterally from corresponding first contact pads 4 tocorresponding second contact pads 2. As shown in FIG. 1C, apertures 14that are formed at least partially through the substrate 12 exposesecond contact pads 2 therethrough.

The substrate 12 may be formed from either a rigid or flexible materialand may comprise a substantially planar member. Silicon or anothersemiconductor material (e.g., gallium arsenide, indium phosphide, etc.)may be used to form the substrate 12 with at least some surfacesthereof, including those that will contact or be located proximate tothe conductive structures of the interposer 20 or another semiconductordevice component to be assembled therewith, being covered with anelectrically insulative material (e.g., a silicon oxide or siliconnitride) to prevent electrical shorting of the conductive structures ofthe interposer 20. Other suitable materials for forming the interposersubstrate 12 include, without limitation, FR-4 resin, glass, ceramics,and polyimide.

The second contact pads 2 of the interposer 20 are arranged to provide adesired pattern, or “footprint”, of electrical connections to facilitatecommunication between at least one semiconductor device to be secured tothe interposer 20 and external electronic devices through a larger-scalesubstrate, such as a circuit board or other carrier.

FIGS. 1B and 1C depict a second contact pad 2 of an interposer 20incorporating teachings of the present invention. Conductive material,such as copper, aluminum, gold, or other conductive material, that iscarried by the substrate 12 forms the second contact pads 2, as well asthe conductive traces 8 and the first contact pads 4. When the secondcontact pads 2 are part of a layer 52 of conductive structures that iscarried upon a surface of the substrate 12, areas of the substrate 12that are superimposed by the second contact pads 2 are substantiallyremoved to form receptacles 11, which facilitate the formation ofelectrical connections between the second contact pads 2 of theinterposer 20 and other components, such as a circuit board or othercarrier. The receptacles 11 are configured to at least partially receiveconductive structures, such as balls, bumps, columns, pins, or otherelements formed from conductive material such as a metal or metal alloy(e.g., solder) or a conductive or conductor-filled elastomer. Generally,it is preferable that the second contact pads 2 have a larger surfacearea than the adjacent end of the receptacle 11 corresponding thereto sothat the substrate 12 will still provide adequate peripheral support foreach second contact pad 2.

Optionally, as shown in FIG. 1C, a protective layer 80 may be formed orpositioned over conductive traces 8 and second contact pads 2, oppositefrom substrate 12. Protective layer 80 may provide additional physicalsupport for second contact pads 2, as well as for conductive traces 8.In addition, protective layer 80 electrically insulates conductivetraces 8 and second contact pads 2. Exemplary materials that may be usedto form protective layer 80 include, but are not limited to, dielectricpolymers, such as polyimide. By way of example only, a dielectricpolymer may be coated over conductive traces 8 and second contact pads 2by known processes (e.g., spin-on coating, use of a doctor blade, screenprinting, sprayed on, etc.) or may comprise a preformed film (e.g.,polyimide tape) that is adhered to substrate 12 over conductive traces 8and second contact pads 2.

The use of receptacles 11 in the interposer 20 of the present inventionmay shorten the physical lengths of circuits between the first contactpads 4 and their corresponding second contact pads 2, which may reduceelectrical inductance relative to that of a more conventional interposerby eliminating the need for conductive vias extending through thethickness of the substrate 12.

Although FIG. 1C depicts a receptacle 11 as exposing a second contactpad 2, the receptacles 11 may alternatively expose a portion of aconductive trace 8, a first contact pad 4, or another feature along aconductive path between a first contact pad 4 and its correspondingsecond contact pad 2. As such, some receptacles 11 may facilitatetesting of particular circuits once conductive structures have beensecured to the second contact pads 2 of the interposer 20 and one ormore semiconductor devices have been assembled therewith.

The receptacles 11 may be formed with draft angles, countersinks,chamfers, or radii or, alternatively, as recesses with substantiallyvertical sides. In addition, the cross-sectional shapes of thereceptacles 11, taken transverse to the depths thereof, may havecircular, rectangular, or other desired shapes. Any process that issuitable for removing material of the type from which the interposersubstrate 12 is formed may be used to form the receptacles 11. Forexample, mask and etch processes may be used to form receptacles 11 in asubstrate 12 that is formed from a semiconductor material, glass, orceramic. Substrates 12 that are formed from resins, or polymers, mayhave receptacles 11 formed therein by mechanical processes, such asdrilling (including laser drilling), punching, milling, or die cutting.

The interposer 20 of the present invention may include a thermallyconductive element 6, which may be formed from a thermally conductivematerial (i.e., a material conducive to heat transfer), such as copper,aluminum, gold, or the like. The thermally conductive element 6 mayincrease the overall thermal mass of the interposer 20 and, thus, act asa so-called “heat sink” for a semiconductor device positioned in thermalcommunication therewith. As depicted, the thermally conductive element 6is located completely within the attach region 7. Alternatively, athermally conductive element 6 may be located only partially within theattach region 7 or lie completely outside of the attach region 7 andproximate thereto. Preferably, the thermally conductive element 6 isconfigured to thermally communicate with a semiconductor device disposedupon the interposer 20 so as to convey heat therefrom during operationof the semiconductor device. By way of example only, the thermallyconductive element 6 may comprise a part of the at least one layer 52 ofconductive structures and may be formed from the same material as one ormore of the other conductive structures of that layer 52. Preferably,the thermally conductive element 6 is electrically isolated from otherelectrically conductive structures of the interposer 20.

The interposer 20 may also include a ground plane 5. The thermallyconductive element 6 and the ground plane 5 may comprise the sameelement or separate elements from one another. Like the thermallyconductive element 6, the ground plane 5 may be positioned completelywithin, partially within, or proximate to an attach region 7 of theinterposer substrate 12.

Some of the receptacles 11 that are formed at least partially throughthe interposer substrate 12 may expose portions of a ground plane 5, athermally conductive element 6, or a contact pad that communicates withthe ground plane 5 and/or thermally conductive element 6. Whenreceptacles 11 are used to facilitate the transfer of heat away from anassembly or package that includes the interposer, the location, volume,and shape of each such receptacle 11 may be tailored to provideparticular heat dissipation characteristics. In addition or in thealternative, grooves (not shown) or other structures may be formedpartially or completely through the interposer substrate 12 to exposeportions of a thermally conductive element 6 and to facilitate thetransfer of heat away from an assembly or package including theinterposer 20. As an example, and not to limit the scope of the presentinvention, structures such as receptacles 11 and/or grooves (not shown)that facilitate the transfer of heat away from the thermally conductiveelement 6 may be distributed across the substrate 12 over roughly thesame area as that occupied by thermally conductive element 6.

As another alternative, shown in FIGS. 2C-2E, an aperture 14′ may beformed through the interposer substrate 12′ to expose a large, centralportion of the thermally conductive element 6 therethrough, with atleast some peripheral regions of the thermally conductive element 6being secured to and supported by the interposer substrate 12′.

Referring now to FIG. 2A, a package 21 including the above-describedinterposer 20 and a semiconductor device 36 (e.g., the illustratedsemiconductor die) affixed thereto is depicted. The semiconductor device36 may be secured to an attach region 7 of the interposer 20 by way of adie attach material 38, such as a suitable adhesive or adhesive-coatedelement. Bond pads 42 of the semiconductor device 36 may be electricallyconnected with corresponding first contact pads 4 of the interposer 20by way of bond wires 32 or other intermediate conductive elements (e.g.,leads, TAB elements carried by a dielectric film, etc.) that are securedto second contact pads 2 formed on the top surface 10 (FIG. 1A) thereof.

In addition, package 21 includes electrically conductive structures 34secured to at least some of the second contact pads 2 of the substrate12′. The electrically conductive structures 34 are positioned at leastpartially within the receptacles 11 formed in the interposer substrate12′ and, thus, are at least partially laterally surrounded by theinterposer substrate 12′. Electrically conductive structures 34 may alsobe secured to a ground plane 5 of the interposer 20 or a contact (notshown in FIG. 2A) that communicates with the ground plane 5.

Thermally conductive structures 50, which resemble and may be formedfrom the same materials as those from which the electrically conductivestructures 34 are formed, may be secured to a thermally conductiveelement 6 of the interposer 20 or to a contact (not shown in FIG. 2A)that communicates with the thermally conductive element 6. As with thethermally conductive element 6, the thermally conductive structures 50may increase the overall thermal mass of a package 21 and, thus, act asa heat sink for the adjacent thermally conductive element 6, as well asfor a semiconductor device 36 in communication with the thermallyconductive element 6. In the event that a single structure forms both aground plane 5 and a thermally conductive element 6, the conductivestructures 34/50 protruding therefrom may be formed from a material thatis both electrically and thermally conductive.

The electrically conductive structures 34 may, by way of example only,comprise balls, bumps, columns, pins, or other structures that areformed from an electrically conductive material, such as a metal, ametal alloy (e.g., solder), a conductive elastomer, or aconductor-filled elastomer. Also by way of example, the thermallyconductive structures 50 may be formed from a metal, a metal alloy, oranother thermally conductive material.

When the electrically conductive structures 34 or thermally conductivestructures 50 comprise solder, another metal alloy, or a metal, thesestructures may be formed, as known in the art, by use of a solder mask40 that has been secured to (in the case of a preformed film soldermask) or formed on (in the case of an applied solder mask material) thesubstrate 12′ of interposer 20. Once the metal or solder structures havebeen formed, the solder mask 40 may remain in place adjacent to theinterposer 20 or, optionally, be removed from the interposer 20.

When one or more semiconductor devices 36 have been secured andelectrically connected to the interposer 20, each semiconductor device36 may be partially or fully covered with an encapsulant material 30 ofa known type, such as a suitable pot mold material, transfer moldmaterial, glob top material, conformal coating material, or the like.Such encapsulant material 30 protects the covered regions of eachsemiconductor device 36, as well as the bond wires 32 or otherintermediate conductive elements that electrically connect the bond pads42 of the semiconductor device 36 and their corresponding first contactpads 4 on the interposer 20.

A package 21 of the present invention may have a total thickness of lessthan about 0.8 mm, making it suitable for use in compact electronicdevices, such as cellular telephones, handheld computers, and portablecomputers, where such low-profile packages are required or desired.

FIG. 2B depicts a variation of package 21, in which the ends of thethermally conductive structures 50 that protrude from the interposer 20are connected to one another by way of a heat transfer element 48. Theheat transfer element 48, which further increases the overall thermalmass of the package 21 and, therefore, provides heat sink properties,effectively increases the surface area from which heat may dissipate andmay, thereby, increase the rate at which the package 21 is able todissipate heat by way of convection or radiation. As shown, the heattransfer element 48 is a substantially planar, unitary structure.Alternatively, the heat transfer element 48 may be formed from a numberof separate sections. The heat transfer element 48 may optionallyinclude holes, cut-outs, varying cross-sectional properties, or thelike, or some combination thereof.

In addition, a surface 51 of the heat transfer element 48 may bemechanically, chemically, or otherwise configured to further enhance theability of the heat transfer element 48 to dissipate heat from thesemiconductor device 36. As examples of chemical treatments of thesurface 51 of heat transfer element 48, processes such as coating,greening, or blackening may be employed to increase the emissivity ofthe heat transfer element 48 for radioactive heat transfer. Examples ofmechanical configuration of the surface 51 of the heat transfer element48 to enhance its heat dissipative properties include geometricalenhancements such as grooves, roughening, or other processes thatincrease the area of the surface 51. Such surface treatments may beeffected before or after the heat transfer element 48 is attached to thethermally conductive structures 50. One or more regions of the surfaceof the heat transfer element 48 may also be coated with dielectricmaterial to prevent electrical shorting.

FIGS. 2C-2E depict another embodiment of a package 21′, which includesan interposer 20′ with an interposer substrate 12′ that includes anaperture 14′ formed therethrough to expose a large portion of thecentral region of a thermally conductive element 6 that underlies a backside 37 of a semiconductor device 36. At least some of the peripheraledges of the thermally conductive element 6 overlap a surface of theinterposer substrate 12′ and are physically supported thereby. Also, thesolder mask 40 of package 21′, if any, does not extend over this portionof the thermally conductive element 6.

The exposed portion of the thermally conductive element 6 may remainexposed through the interposer substrate 12′, as depicted in FIG. 2C.Any exposed regions of the surface of the thermally conductive element 6may be chemically or mechanically treated in such a way as to enhancethe thermally dissipative properties thereof, as well as to form anelectrically insulative coating thereon. Alternatively, as shown in FIG.2D, the package 21′ may include thermally conductive structures 50 thatare positioned within the aperture 14′, secured to and protrude fromexposed regions of the thermally conductive element 6, and are at leastpartially laterally surrounded by the interposer substrate 12′. FIG. 2Edepicts another alternative, in which the package 21′ includes a heattransfer element 48 secured to thermally conductive structures 50 thatare secured to and protrude from the thermally conductive element 6.

Turning now to FIG. 5, another exemplary embodiment of interposer 20″according to the present invention is depicted. Interposer 20″ includesa receptacle 22 that is configured to at least partially receive asemiconductor device 36 to be electrically connected thereto. Theremaining features of interposer 20″ are substantially the same as thoseof interposer 20 shown in FIGS. 1A-1C.

FIG. 6 depicts another embodiment of an interposer 120, of which thefirst contact pads 4 are positioned in an attach region 7 and positionedto mirror the locations of bond pads 42 so as to facilitate flip-chipattachment of a semiconductor device 36 thereto. The remaining featuresof interposer 120 are substantially the same as those of interposer 20shown in FIGS. 1A-1C.

Referring to FIG. 7, another embodiment of interposer 120″ is depicted.Interposer 120″ includes a receptacle 22″ formed in the same surface asthat to which receptacles 11 open. Receptacle 22″ is configured to atleast partially receive a semiconductor device 36 in a flip-chiporientation. Accordingly, first contact pads 4″ are positioned withinthe receptacle 22″. Conductive traces 8″ that communicate with the firstcontact pads 4″ extend across the interposer substrate 12″, either on asurface thereof, as shown, or internally therethrough. The conductivetraces 8″ extend laterally to the locations of corresponding secondcontact pads 2″, which are exposed through the receptacles 11 that areformed through the interposer substrate 12″ so as to at least partiallyexpose corresponding second contact pads 2″.

Turning now to FIG. 3, an exemplary embodiment of a multi-chip module 60according to the present invention is depicted. As shown, the multi-chipmodule 60 includes two packages 121: an upper package 121U and a lowerpackage 121L.

At least the lower package 121L of such a multi-chip module 60 includesan aperture 9 formed through the top of the encapsulant material 30thereof. Each aperture 9 is configured to at least partially receive acorresponding conductive structure 34 that protrudes from the bottom ofan overlying upper package 121U. A contact pad of a third set, whichcontact pad is referred to herein as a third contact pad 16, is exposedwithin each aperture 9.

Some third contact pads 16 of the package 121 may communicate withcorresponding first contact pads 4 and, thus, ultimately, with the bondpads 42 and corresponding internal circuitry a semiconductor device 36of the package 121 by way of a conductive trace 8 positioned between thethird contact pad 16 and the corresponding first contact pad 4. Somethird contact pads 16 of the package 121 may communicate withcorresponding second contact pads 2 and, thus, ultimately with one ormore electronic components that are external to the package 121 by wayof a via 15 or other conductive element positioned between the thirdcontact pad 16 and the corresponding second contact pad 2. Thus, aconductive structure 34 that protrudes from an upper package 121U andits corresponding third contact pad 16 of the next-lower package 121Lmay facilitate communication between a semiconductor device 36 of theupper package 121U and either a semiconductor device 36 of thenext-lower package 121L or an external electronic device.

Based on an overall package height of about 0.8 mm (assuming the heightthat the encapsulant material 30 protrudes above the interposer 20 isabout 0.5 mm, that the receptacles 11 extend completely through theinterposer 20, and that the electrically conductive structures 34therein have heights of about 0.3 mm), the overall thickness of themulti-chip module 60 depicted in FIG. 3 may be about 1.5 mm since theapertures 9 at least partially receive the heights of the electricallyconductive structures 34 that protrude from the upper package 121U.

While FIG. 3 depicts a multi-chip module 60 that includes two verticallystacked packages 121U and 121L, it will be understood that a multi-chipmodule incorporating teachings of the present invention may include morethan two packages.

Another exemplary embodiment of multi-chip module incorporatingteachings of the present invention may be formed by securing multiplesemiconductor devices to a single interposer. The semiconductor devicesmay be positioned at different locations on the interposer, as shown inFIG. 8, or stacked over one or more locations of the interposer, asshown in FIGS. 4A-4D.

With reference to FIG. 4A, a multi-chip module 70 that includes a singleinterposer 20 with semiconductor devices 36, 36′ stacked over the sameattach region 7 thereof is depicted. The lower semiconductor device 36is secured to the interposer 20 by way of a die attach material 38,while another quantity of die attach material 39, such as a suitableadhesive or adhesive-coated element, secures the upper semiconductordevice 36′ to the lower semiconductor device 36. Intermediate conductiveelements, such as the depicted bond wires 32, 32′, electrically connectrespective bond pads 42, 42′ of the semiconductor devices 36, 36′ tocorresponding first contact pads 4, 4′ of the interposer 20.

The multi-chip module 70 may also include electrically conductivestructures 34 and/or thermally conductive structures 50 that communicatewith second contact pads 2 (FIGS. 1A-1C) and a thermally conductiveelement 6, respectively.

Such a multi-chip module 70 assembly may be packaged, as known in theart, such as by applying a suitable encapsulant material 30 (e.g., aglob-top type encapsulant, a transfer molded or pot molded typeencapsulant, etc.) over at least portions of semiconductor devices 36,36′, the intermediate conductive elements (e.g., bond wires 32, 32′),and at least portions of the interposer 20.

In FIG. 4B, a multi-chip module 70′ that includes a plurality ofsemiconductor devices 36, 36′ and an interposer 20′ of the type depictedin FIGS. 2A-2C is illustrated. In the depicted example, the thermallyconductive structures 50 of the multi-chip module 70′ are positionedwithin the aperture 14′ formed through the substrate 12′ of theinterposer 20′ and are secured directly to the thermally conductiveelement 6. In addition, the multi-chip module 70′ may include a heattransfer element 48 secured to at least some of the thermally conductivestructures 50. FIG. 4C illustrates an embodiment of multi-chip module70′ in which the thermally conductive element 6 is exposed through theaperture 14′ formed through the interposer substrate 12′.

Also, as shown in FIGS. 4C and 4D, a second thermally conductive element6′ may be positioned over an active surface 35′ of the uppersemiconductor device 36′ to facilitate the dissipation of heattherefrom. Of course, in order to provide the desired heat transfercharacteristics, at least a portion of the second thermally conductiveelement 6′ may be exposed through an encapsulant material 30 that coversportions of the upper semiconductor device 36′. As with thermallyconductive element 6, one or more surfaces of the second thermallyconductive element 6′ may be chemically or mechanically treated so as toimprove the heat dissipation characteristics thereof.

As depicted in FIG. 8, an interposer 20′″ with more than one attachregion 7 thereon may be used to form a multi-chip module 70′″ withsemiconductor devices 36 at different lateral positions. Of course, eachsemiconductor device 36 may be secured and electrically connected tosuch an interposer 20′″ as described above with reference to FIG. 2A.

Although the foregoing description contains many specifics, these shouldnot be construed as limiting the scope of the present invention, butmerely as providing illustrations of some exemplary embodiments.Similarly, other embodiments of the invention may be devised which donot depart from the spirit or scope of the present invention. Featuresfrom different embodiments may be employed in combination. The scope ofthe invention is, therefore, indicated and limited only by the appendedclaims and their legal equivalents, rather than by the foregoingdescription. All additions, deletions, and modifications to theinvention, as disclosed herein, which fall within the meaning and scopeof the claims are to be embraced thereby.

1. An interposer for use in a semiconductor device assembly or package,comprising: an interposer substrate; at least one conductive structurecomprising at least one of a thermally conductive element and a groundplane carried by a surface of the interposer substrate and configured tocommunicate with a back side of a semiconductor die; a plurality ofcontact pads laterally offset from the at least one conductive structureand electrically isolated therefrom; and at least one recess in asurface of the interposer substrate opposite the surface carrying the atleast one conductive structure, the at least one recess exposing the atleast one conductive structure.
 2. The interposer of claim 1, furthercomprising: another plurality of contact pads, each contact pad of theanother plurality being laterally offset from a contact pad of theplurality of contact pads.
 3. The interposer of claim 2, furthercomprising: a plurality of conductive traces extending between at leastsome contact pads of the plurality and corresponding contact pads of theanother plurality.
 4. The interposer of claim 3, wherein at least aportion of at least one of the plurality of conductive traces is carriedwithin the interposer substrate.
 5. The interposer of claim 3, whereineach of the plurality of contact pads, the plurality of conductivetraces, and the another plurality of contact pads is at least partiallycarried upon a same, substantially planar surface of the interposersubstrate.
 6. The interposer of claim 5, wherein at least one attachregion is located on the same substantially planar surface of theinterposer substrate as the plurality of contact pads, the plurality ofconductive traces, and the another plurality of contact pads are carriedupon.
 7. The interposer of claim 2, further comprising: a plurality ofrecesses formed in a surface of the interposer, at least partiallythrough the interposer substrate and in alignment with at least somecontact pads of the plurality of contact pads or the another pluralityof contact pads.
 8. The interposer of claim 7, wherein at least oneattach region is located on a surface of the interposer substrateopposite the surface in which the plurality of recesses is formed. 9.The interposer of claim 7, wherein at least one attach region is locatedupon the same surface of the interposer substrate as that in which theplurality of recesses is formed.
 10. The interposer of claim 2, furthercomprising: at least one upper contact pad accessible from a surface ofthe substantially planar interposer substrate opposite from that atwhich the plurality of contact pads or the another plurality of contactpads are accessible.
 11. The interposer of claim 1, further comprising:a plurality of recesses formed in the opposite surface of the interposersubstrate to expose at least portions of the plurality of contact pads.12. A semiconductor device assembly, comprising: an interposerincluding: a substantially planar surface carrying contact pads and atleast one conductive structure comprising at least one of a thermallyconductive element and a ground plane; and a surface opposite thesubstantially planar surface and including at least one recess thereinexposing the at least one conductive structure; and at least onesemiconductor device including: a back side in communication with the atleast one conductive structure; and bond pads that communicate withcorresponding contact pads of the interposer.
 13. The semiconductordevice assembly of claim 12, further comprising: at least one discreteconductive element secured to the at least one conductive structure. 14.The semiconductor device assembly of claim 13, wherein the at least onediscrete conductive element is at least partially laterally surroundedby the interposer.
 15. The semiconductor device assembly of claim 12,wherein contact surfaces of the contact pads are recessed relative to asurface of the interposer.
 16. The semiconductor device assembly ofclaim 15, wherein the at least one semiconductor device is secured tothe same surface as that in which the contact surfaces are recessed. 17.The semiconductor device assembly of claim 16, wherein the at least onesemiconductor device is secured and electrically connected to theinterposer in a flip-chip orientation.
 18. The semiconductor deviceassembly of claim 15, wherein the at least one semiconductor device issecured to an opposite surface from that in which the contact surfacesare recessed.
 19. The semiconductor device assembly of claim 18, whereinthe interposer comprises a recess configured to at least partiallyreceive the at least one semiconductor device.
 20. The semiconductordevice assembly of claim 15, wherein the contact pads are carried uponan opposite surface of the interposer than that in which contactreceptacles in which the contact pads are recessed are formed.
 21. Thesemiconductor device assembly of claim 12, wherein the interposercomprises a recess configured to at least partially receive the at leastone semiconductor device.
 22. The semiconductor device assembly of claim12, wherein the at least one conductive structure is in contact with atleast a portion of the back side of the at least one semiconductordevice.
 23. The semiconductor device assembly of claim 15, wherein theat least one recess is formed in the same surface of the interposer asthat in which the contact pads are recessed.
 24. A method forfabricating an interposer, comprising: providing a substantially planarinterposer substrate with a conductive layer on a surface thereof;patterning the conductive layer to form contact pads and at least oneconductive structure for communicating with a back side of asemiconductor device; and forming at least one recess including taperedside walls in an opposite surface of the substantially planar interposerto expose the at least one conductive structure.
 25. The method of claim24, wherein patterning the conductive layer comprises patterning theconductive layer to form conductive traces extending laterally from thecontact pads and outer contact pads at an opposite end of the conductivetraces from the contact pads.
 26. The method of claim 25, furthercomprising: forming a plurality of recesses in the opposite surface ofthe substantially planar interposer substrate to expose at leastportions of the contact pads.
 27. The method of claim 24, furthercomprising: forming a plurality of recesses in the opposite surface ofthe substantially planar interposer substrate to expose at leastportions of the contact pads.
 28. The method of claim 24, furthercomprising: forming the conductive layer on the surface of thesubstantially planar interposer substrate.
 29. The method of claim 24,further comprising: forming at least one recess for at least partiallyreceiving at least one semiconductor device in a surface of thesubstantially planar interposer substrate.
 30. The method of claim 29,wherein forming the at least one recess is effected in the same surfaceas that upon which the conductive layer is located.
 31. The method ofclaim 29, wherein forming the at least one recess is effected in adifferent surface than that upon which the conductive layer is located.32. A method for designing an interposer, comprising: configuring asubstantially planar interposer substrate; configuring at least oneattach location on a surface of the substantially planar interposersubstrate; configuring contact pads on the surface of the substantiallyplanar interposer substrate; configuring at least one conductivestructure comprising at least one of a thermally conductive element anda ground plane to be carried at least partially by the at least oneattach location for communicating with a back side of a semiconductordie secured to the at least one die attach location; and configuring atleast one recess in an opposite surface of the substantially planarinterposer substrate to expose the at least one conductive structure atthe opposite surface.
 33. The method of claim 32, further comprising:configuring conductive trace locations to be carried by thesubstantially planar interposer substrate; and configuring outer contactpad locations to be carried by the substantially planar interposersubstrate, each outer contact pad location being configured to be offsetfrom a corresponding contact pad location, each conductive tracelocation being configured to extend between a contact pad location and acorresponding outer contact pad location.
 34. The method of claim 32,further comprising: configuring a plurality of recesses to be formed inthe opposite surface of the substantially planar interposer substrate toat least partially expose corresponding contact pads.
 35. The method ofclaim 34, wherein configuring the at least one attach location comprisesconfiguring the at least one attach location on the same surface of thesubstantially planar substrate as that in which the plurality ofrecesses is configured.
 36. The method of claim 34, wherein configuringthe at least one attach location comprises configuring the at least oneattach location in an opposite surface of the substantially planarsubstrate from that in which the plurality of recesses is configured.37. The method of claim 32, further comprising: configuring a pluralityof recesses to be formed in the substantially planar interposersubstrate to expose the contact pads.
 38. The method of claim 32,wherein configuring the at least one conductive structure comprisesconfiguring at least one thermally conductive element location at leastpartially within the at least one attach location.
 39. The method ofclaim 38, further comprising: configuring a plurality of recesses in theopposite surface to expose the contact pads.
 40. The method of claim 32,wherein configuring the at least one conductive structure comprisesconfiguring at least one ground plane at least partially within the atleast one attach location.
 41. A method for forming a semiconductordevice assembly, comprising: securing at least one semiconductor deviceto a conductive structure comprising at least one of a thermallyconductive element and a ground plane at an attach location of asubstantially planar interposer with a back side of the at least onesemiconductor device communicating with the conductive structure, theconductive structure exposed through at least one recess in a surface ofthe substantially planar interposer opposite a side of the conductivestructure to which the at least one semiconductor device is secured; andelectrically connecting the at least one semiconductor device with theinterposer.
 42. The method of claim 41, wherein providing the interposercomprises providing an interposer with recessed contact pads.
 43. Themethod of claim 42, further comprising: securing at least one discreteconductive element to the conductive structure, the at least onediscrete conductive element being at least partially laterallysurrounded by the interposer.
 44. The method of claim 42, whereinelectrically connecting the at least one semiconductor device comprisessecuring the at least one semiconductor device to the same surface ofthe interposer as that in which the contact pads are recessed.
 45. Themethod of claim 42, wherein electrically connecting the at least onesemiconductor device comprises securing the at least one semiconductordevice to an opposite surface of the interposer as that in which thecontact pads are recessed.
 46. The method of claim 41, furthercomprising: at least partially encapsulating at least the at least onesemiconductor device.